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Asked: 2026-05-11T02:33:39+00:00

Has anyone seen this error when trying to call an external C function from

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Has anyone seen this error when trying to call an external C function from an Oracle query? I’m using Oracle 10g and get this error every time I try to call one of the two functions in the library. A call to the other function returns fine every time, though the function that works is all self-contained, no calls to any OCI* functions.

Here’s the stored procedure that is used to call the failing C code:

CREATE OR REPLACE PROCEDURE index_procedure(text in clob, tokens in out nocopy clob, location_needed in boolean) as language c name 'c_index_proc' library lexer_lib with context parameters (   context,   text,   tokens,   location_needed );

Any help would be appreciated. Everything I’ve found on this error message says that the action to take is: Contact Oracle customer support.

Edit: I’ve narrowed it down to the point that I know that there is a segfault deep in libclntsh after I call OCILobTrim (to truncate it down to 0 length) on the tokens clob. Here is the code I’ve been using to call this procedure.

declare text CLOB; tokens CLOB; begin dbms_lob.createtemporary(tokens, TRUE); dbms_lob.append(tokens, 'token'); dbms_lob.createtemporary(text, TRUE); dbms_lob.append(text, '<BODY>Test Document</BODY>'); index_procedure(text, tokens, FALSE); dbms_output.put_line(tokens); end; /

Is there something wrong with this setup that might be causing OCILobTrim problems?

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  1. Well, an upgrade to 10.2.0.4 (was using 10.2.0.1) at least gave me an understandable error instead of a fairly useless core file and the ORA-28579.

    It turns out that the code I was debugging was assuming that calling OCILobRead would return all of the data in one pass. This is the case for any client using a fixed width character set.

    For clients using a variable width character set, this isn’t the case, OCILobRead was actually reading part of the data and returning OCI_NEED_DATA and future calls to OCILobTrim and OCILobWrite were failing because of the still pending call to OCILobRead. The solution was to loop OCILobRead calls until OCI_NEED_DATA was no longer returned and we had all of the needed data in our buffer.

    A call to OCIBreak also would have allowed the OCILobTrim and OCILobWrite functions to continue, though we wouldn’t have had all of the needed input data.

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